Monday, September 16, 2013

Abstract-Terahertz responsivity of field-effect transistors under arbitrary biasing conditions



Péter Földesy
Computer and Automation Research Institute, Hungarian Academy of Sciences, Budapest 1111, Hungary and Pázmány Péter Catholic University, Faculty of Information Technology, Budapest 1083, Hungary 


Current biased photoresponse model of long channel field-effect transistor (FET) detectors is introduced to describe the low frequency behavior in complex circuit environment. The model is applicable in all FET working regions, including subthreshold, linear, saturated modes, includes bulk potential variations, and handles the simultaneous gate-source and drain-source detection or source-driven topologies. The model is based on the phenomenological representation that links the photoresponse to the gate transconductance over drain current ratio (gm/ID) and circuit theory. A derived method is provided to analyze the detector behavior, to characterize existing antenna coupled detectors, and to predict the photoresponse in a complex circuit. The model is validated by measurements of 180 nm gate length silicon and GaAs high electron mobility FETs.

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